Moed Katan 3:3-4

Moed Katan 3:3

The following documents may be written on chol hamoed: marriage contracts, divorce papers, receipts, wills, gifts, a prozbul (document transferring one’s debts to the court for collection), appraisals, sustenance commitments, chalitzah papers (to release a woman from yibum), refusal documents (for the marriage of a minor orphan girl, in lieu of a divorce), documents choosing judges for litigation, court orders and government documents.

Moed Katan 3:4

One may not write a promissory note on chol hamoed unless the lender does not trust the borrower or the scribe needs his fee to buy food. One may not write religious texts, tefillin or mezuzos on chol hamoed, nor correct even one letter, not even in the scroll read in the Temple. Rabbi Yehuda said that a person may write tefillin and mezuzos for his own use and spin techeiles (the blue wool for tzitzis) in his lap (i.e. in an unusual fashion).